Hard disk devices have conventionally been used in information processing equipment such as computers. Hard disk devices are now mounted not only as external storage devices for computers but also in home appliances such as televisions and camcorders, and automotive electronics.
A conventional hard disk device 200 illustrated in FIG. 27 has a drive mechanism housed in a casing body 201. The drive mechanism has a spindle 203 that rotatably drives a hard disk 202 as a recording medium (the spindle is rotated by a motor not-shown in the drawing), a carriage 205 that supports a magnetic head 204 recording information and reading information on/from the hard disk 202 and pivots over a surface of the hard disk 202, a VCM (Voice Coil Motor) 206 that allows the carriage 205 to precisely pivot to control scan with the magnetic head 204, a pivot shaft 207 that is fixed to the casing body 201 and joins the casing body 201 to the carriage 205, and a tolerance ring 208 that fixes the carriage 205 and the pivot shaft 207 to each other. The pivot shaft 207 is, for example, approximately shaped like a column and has a structure of a bearing.
The carriage 205 pivots about the pivot shaft 207 as the center axis over the surface of the hard disk 202. The carriage 205 is fixed to the pivot shaft 207 with the tolerance ring 208 interposed therebetween, thereby preventing motive power exerted to pivot the carriage 205 by the VCM 206 from being transferred to the casing body 201.
The conventional tolerance ring, for example, as the tolerance ring 208 illustrated in FIG. 28, has a plurality of projections 208b (contact portions) on the outer peripheral surface of a base 208a formed of a flat plate-shaped member approximately wound around in a predetermined direction into a ring shape, the projections 208b each protruding to be convex from an approximately rectangular region along the outer edge of the flat plate. After the tolerance ring 208 is inserted into an opening in the carriage 205, the pivot shaft 207 is press-fitted into the inside of the tolerance ring 208.
As such a tolerance ring, a tolerance ring having a plurality of convex contact portions protruding on the outer peripheral side is disclosed (see, for example, Patent Literatures 1 to 5). In the tolerance ring disclosed in Patent Literatures 1 to 5, the contact portions are in pressure-contact with the side surface of one of the carriage 205 and the pivot shaft 207 to fix the carriage 205 and the pivot shaft 207 to each other. The contact portions of the tolerance ring disclosed in Patent Literature 5 are shaped like a rounded curve in the cross section cut along the plane orthogonal to the main surface of the tolerance ring.